There is good reason why we sometimes put love instead of “like”
Korean “like” is much nearer to love than the Engish one. In English, like is something more shallow. You can like a woman, hang out with her, make out with her, maybe also have sex with her, go on dates etc. But in Korean dramas we’ve heard
“I like you too, I cannot live without you”
“I like you. Will you marry me?”
“What happened to you? You don’t eat, you’ve lost your sleep, you act like a crazy person. Do you perhaps like that girl?”
“We like each other so much. Our love may be destined, in that case we’ll meet again” (this was on a web drama I watched yesterday).
“I… I wanted to tell you I like you” Then, to her friend: “Hey, X confessed his love for me yesterday”
From these examples you may understand that for them, “like” is much nearer to “love” than it is for other languages. In cases like this, “like” would sound ridiculous and inadequate, even cheap.
Yes, “love” IS a step further, and they don’t say it easily, and sometimes they even make the distinction among the two:
“I like you… No, I love you!”
(Sorry I am not putting my sources here, I don’t remember, but I assure you that all these are from real dramas)
It’s the same in Chinese, they also have these two verbs (Wǒ xǐhuān nǐ and woaini), and from my limited viewing experience, exactly the same thing happens with those too.
How to translate? It’s a question of context, and common sense should be used. In some cases we could also use “I’m in love with you” instead of “I love you”, as there is a small nuance of difference in English. In teenage dramas we could also use “have a crush on”.
As for the insults, you’re right that they always put something heavier in English.This has been discussed a lot here. You may want to check out those threads: